Gas furnace



NEIL M MURCHIE SCHRANK June 25, 1957 GAS FURNACE Filed March 23, 1955 14- k gd a '@M AQZ AMH Q MMg QQ Unite GAS FURNACE Neil McMurchie Schrank, Maidstone, Saskatchewan, Canada My invention relatm to space heating devices, more particularly having reference to a furnace for use of either natural or manufactured gas.

The present invention contemplates provision of a gas burner within a furnace casing, including an improved draft arrangement with primary and secondary air inlets, whereby excess m'r is supplied to the flame through the secondary inlet, and an improved draft outlet which allows the excess air and relatively cool heavier gases to escape independently for the most part of the burned lighter gases.

One of the objects of the invention is accordingly to provide a space heating furnace for the use of either natural or manufactured gas and incorporating therein an improved arrangement of primary and secondary air inlets for a combustion chamber and burner.

A further object of the invention is to provide an improved draft outlet for the furnace that is graduated to provide a relatively small outlet portion for lighter hot burned gases and a larger outlet portion for excess air and the heavier relatively cool gases to escape.

Other features and advantages of the invention will become apparent by reference to the accompanying description taken in conjunction with the drawings wherein like characters of reference indicate like parts throughout the several views, and wherein:

Fig. 1 is a side view partly broken away and partly in section of a gas furnace embodying my improvements.

Fig. 2 is a front view of same, shown as with the furnace door open and partly broken away, and with the primary air inlet and burner removed.

Fig. 3 shows a fragment of the interior of the furnace and including a broken away portion of the flue outlet pipe, showing particularly the inverted V shaped draft outlet.

Fig. 4 is a side view, partly broken away and partly in section, of the burner and secondary draft chamber and primary air and gas inlet assembly, including the pilot bracket.

Having reference to the drawings there is provided an outer casing 1 with inlet 2 and closure 3 for access to the interior of the casing, the casing being of a character common in furnace construction and including a draft inlet chamber 4 below and separated from the combustion chamber by a partition 5, and a flue outlet pipe 6.

Within the interior of the casing 1 is mounted a secondary casing 7 forming a draft chamber on the partition 5, the casing 7 having an open under-side and the partition having an opening corresponding to the open under side of the secondary chamber. in this chamber 7 is mounted a burner 8 with ignition port 9, said burner having a primary air inlet pipe 14 communicating with the under side and a flame outlet 10 in the upper side; and the upper side further is spaced below the top of the secondary draft chamber to leave an air gap for secondary air. The secondary chamber has a flame outlet 12 aligned with the burner outlet 10. The burner further includes a series of inlets 13 in the lower portion thereof.

The primary air is supplied by means of a pipe assembly 14 suspended within the draft inlet chamber 4 by means of a bracket 15, this assembly including a bell States Patent Patented June 25, 1957 20, a draft control plate 16 threaded on a gas inlet pipe 17, a spider 16 in which the pipe 17 is carried and a pipe section 21 connecting to the burner chamber 8.

The furnace further includes a flue chamber 18 on the casing 1, externally of the casing and having communication therewith by an inverted V shaped draft outlet 19. The chamber 18 discharges through the flue pipe 6.

In the use of the device, additional to the primary air supplied to the burner through the assembly 14 a secondary air supply enters through the chamber 4 and passes through the space between the secondary draft chamber 7 and burner 8. On discharge through the outlet 12 the flame is encircled by an intentionally large amount of excess air, which, by its weight, drops to the lower part of the casing 1, Where it serves to condense the water vapor caused by the combustion process. This cool heavier gas discharges through the lower part of the flue outlet 19 substantially independent of the escape of the lighter hot burned gases through the upper part of the outlet 19. This arrangement has been found to give improved heating in the furnace casing by the separation of the lighter and heavier gases. Mingling of these gases occurs in the flue chamber 18, from which a reading can be taken as is commonly done.

Tests have shown that the flue outlet of a furnace constructed in accordance with this conception is practically free from carbon monoxide under wide variations of conditions and is economical in the use of fuel.

While I have herein disclosed a preferred embodiment of my invention, it is obvious that changes in the construction and arrangement thereof would be readily conceivable, and in so far as such changes come within the spirit and scope of the invention as defined in the appended claim they would be considered a part hereof.

Having thus particularly described and ascertained the nature of my said invention, what I claim and wish to secure by Letters Patent is:

In a gas furnace providing a main casing and a burner unit, a partition in the main casing dividing said casing to provide a combustion chamber in the upper portion in which the burner unit is housed and a draft inlet chamber in the lower portion, said casing having a draft inlet communicating with the draft inlet chamber, and said casing providing a combustion gas outlet, at cylindrical secondary casing supported on said partition and in which secondary casing the burner unit is mounted, said burner unit including a cylindrical chamber and the secondary casing and burner unit providing an annular space therebetween, the secondary casing having a draft inlet in the under side from the draft inlet chamber to said annular space and an outlet in the upper side through which the burner unit discharges, the upper side of the secondary casing being spaced from the upper end of the burner unit chamber to leave an outlet passage therebetween from the annular space to the outlet in the upper side of the secondary casing, and means forming a flue chamber on the main casing to which the combustion gas outlet discharges, said main casing having an opening in the side thereof forming said combustion gas outlet extending downwardly from a level above said secondary chamber to the level of said partition, said opening having a capacity which increases downwardly from the uppermost portion and is uniformly graduated to reach its greatest discharge capacity at the extreme lower portion.

References Cited in the file of this patent UNITED STATES PATENTS 384,683 Dinsmore June 19, 1888 1,885,891 Breese Nov. 1, 1932 2,154,706 Shaffer Apr. 18, 1939 2,219,276 Young Oct. 22, 1940 

